As far as the motives of hackers goes, I would have thought that your average hacker gets his kicks from the success of breaking into someone's computer, not from some altruistic desire to reveal the 'truth' (whatever that may be) into the public domain.
I don't mean the word hacker in the sense the word is used in popular media.
The German CCC*, the EFF or the Pirate Parties would be example of other political organisations that spring from the hacker ethos. All three actively support Wikileaks.
Those organisations also lead the fight against government surveillance.
I'm not saying I'm necessarily against what Wikileaks are doing, but they seem to be a self appointed organization who decide themselves what information they will release or withold
That's not really true. They promise that they will release all authentic documents that they get with fulfill the significance criteria.
Julian Assange for example believes that global warming is likely happening but still released the Climategate emails.
In the last year Wikileaks didn't didn't release a lot of material that wasn't related to the US. One thing that they released was a public plan about the organisation of the German loveparade in which a bunch of people died.
Still it's worthy of criticism that Wikileaks didn't release more documents from their trove that aren't related to the US. Wikileaks defense is that they don't have the man power to check enough documents. They also have some technical problems with their infrastructure that they want to rebuild.
Their submission page is at the moment down because they can't keep up their new documents. They promise to release the documents that they still hold which fulfill the above criteria and put the submission page back online in the future.
Because of the issue a few people who come from the adjacency of the CCC quited actively being evolved in Wikileaks to start a competing project that can be more transparent and more decentralized. On of them is the former Wikileaks spokesperson Daniel Domscheit-Berg.
The Wau Holland foundation however still manages Wikileaks money. Wau Holland was a cofunder of the CCC.
If Wikileaks however loses the public debate that not only means that Wikileaks will be shut down but that other project with a bit more transparency would also be impossible.
Furthermore, Wikileaks are pretty sensitive themselves about any investigations being done into their own business. Their founder, Assange, is still in hiding, and is currently being sought by the Swedish police on a charge of rape.
According to Assange's lawyer the UK police knows the location of Assange. The UK police didn't issue a denial.
Given that there are people who call for Assange's assassination I think it's perfectly reasonable for him to reside a location that's not publically known to everyone.
It also would be really hard for Assange to hide in a ECHELON covered country. If normal people see him on the street and tell their friends via telephone or EMail that enough for ECHELON to locate Assange. He's a public face and therefore can't hide from the US.
*For full disclosure, I attended the last two congresses of the CCC but I'm no formal member of the club.